Soares W C, Moura A L, Canabarro Askery, de Lima E, Lopes J H, Fonseca E J S, Felisberto M L, de Lima Bernardo B, Hickmann J M, Chávez-Cerda S
Appl Opt. 2020 Jul 1;59(19):5687-5692. doi: 10.1364/AO.394745.
The orbital angular momentum conservation of light reveals different diffraction patterns univocally dependent on the topological charge of the incident light beam when passing through a triangular aperture. It is demonstrated that these patterns, which are accessed by observing the far-field measurement of the diffracted light, can also be obtained using few photon sources. In order to explain the observed patterns, we introduce an analogy of this optical phenomenon with the study of diffraction for the characterization of the crystal structure of solids. We demonstrate that the finite pattern can be associated with the reciprocal lattice obtained from the direct lattice generated by the primitive vectors composing any two of the sides of the equilateral triangular slit responsible for the diffraction. Using the relation that exists between the direct and reciprocal lattices, we provide a conclusive explanation as to why the diffraction pattern of the main maxima is finite. This can shed a new light on the investigation of crystallographic systems.
光的轨道角动量守恒揭示了在通过三角形孔径时，不同的衍射图案唯一地取决于入射光束的拓扑电荷。结果表明，通过观察衍射光的远场测量所获得的这些图案，也可以使用单光子源得到。为了解释所观察到的图案，我们将这种光学现象与用于表征固体晶体结构的衍射研究进行类比。我们证明，有限图案可以与从由构成负责衍射的等边三角形狭缝任意两边的原向量生成的正晶格得到的倒易晶格相关联。利用正晶格和倒易晶格之间存在的关系，我们对主极大值的衍射图案为何是有限的提供了一个确凿的解释。这可以为晶体学系统的研究提供新的思路。
